Professional editing has moved from ‘linear’ (non-random access, typically from tape) to nonlinear (random access, typically from hard disk or disk array), but the acquisition and archive media is typically still tape. Controlling video sources and sinks (e.g., tape decks) has required separate control channels, hardware and software (e.g., from VLAN, or edit control panels). The control units require control inputs and software to communicate with these systems (e.g., using linear time code and RS422 or serial ports). Alternatively, professional video equipment can embed time codes in the video signal itself, such as a vertical interval time code, to control the recorder. The Vertical Interval Time Code (VITC), however, is difficult to use; it requires (i) that the tape be pre-formatted (a time consuming process), (ii) that the vertical blanking interval (VBI) is preserved through the video distribution network (it typically is stripped and regenerated at each node), and (iii) prior knowledge of the location of VITC in the signal so that the recording device can be properly configured to record that program. (VITC can appear on various lines in the VBI, and different sets of VITC can be present on the same tape).
With the proliferation of camcorders, video acquisition and editing is transitioning from the professional domain to the consumer domain. Recent product introductions in personal computing (e.g., Macintosh) and DVD recording have further moved recording and editing into the consumer domain. In the consumer space, a bus referred to as Firewire (IEEE1394) and its audio/video control (AV/C) protocol integrates both control and data transfer on the same wire to control a video source and a recording device. This scheme is an improvement in that it eliminates the need for a second bus. The drawbacks of this scheme is that the 1394 bus carries compressed MPEG or DV data only and requires an audio-video controller (AV/C) or target unit and sub-unit software on both devices to control and synchronize the data transfers (start or start record). Also, both the camcorder and the recording device must support the 1394 standard and implement the AV/C protocol in a compatible way to take advantage of the standard.
For camcorder formats such as 8 mm, Hi-8, VHS, or Compact VHS, IEEE 1394 is not an option. In order to record video clips onto VHS tapes, using devices without IEEE 1394, such as a camcorder and VCR, the user must connect video and audio cables from the camcorder to corresponding input jacks (RCA) on the VCR. Using controls on the camcorder, the user locates the starting position of the segment to be recorded. Typically, the user uses fast forward, reverse, slow motion, and pause modes on the camcorder. When the desired segment is found, the user presses normal “play” mode on the camcorder. The user must then press “record” on the VCR to begin the recording. Thus, the user is required to manually synchronize the recorder with the camcorder, not just for recording, but also for stopping and pausing the recording.
Although consumer editing may not require the level of control and synchronization that professional equipment or even 1394 offers, it would be desirable to have an inexpensive and generic system that synchronizes data transfers between a source device with a recording device without the need for user inter-action or an extra control channel or on the source device. The present invention addresses such a need.